Electron tube base



- 1941- B. A. COFFIN ELECTRON TUBE BASE Filed Aug. 2, 1940 Patented Dec. 9, 1941 .UNITED STATES PATENT QFFICE ELECTRON TUBE BASE Bruce A. Coffin, Peabody, Mass.

Application August 2, 1940, Serial No. 349,766

4 Claims.

This invention relates to an electrical connector and specifically to the base structure of an electronic tube or device.

The invention has for one object to provide a novel and improved electrical connector and specifically a base structure for a tube of the type provided with a central metallic shield member for the purpose of afiording an electromagnetic and electrostatic shield between the stem connection leads and the base connection pins or members of the connector or tube, and in which provision is made for electrically and mechanically connecting the shield member to a ground connection terminal in a simple and efficient manner whereby to reduce to a minimum the number of assembly operations whereby to effect a substantial economy in the cost of production of the device.

Another and more specific object of the invention is to provide a novel and improved central metallic shield member for a tube having provision for securing the shield to a ground connection terminal and. whose construction is such as to facilitate assembling of the shield with the vacuum tube whereby to effect an economy in the cost of production of the tube.

A further object of the invention is to provide a novel and improved base for an electrical connector and specifically a tube of the character describedincluding an outer metallic shell forming part of the base and in which provision is made for connecting said shell and a metallic shield to a ground connection terminal in a simple, economical and efficient manner.

With these general objects in View and such others as may hereinafter appear, the invention consists in the electrical connection, and in the tube, and in the various structures, arrangements and combinations of parts hereinafter described and particularly defined in the claims at the end of this specification.

In the drawing illustrating the preferred embodiment of the invention, Fig. l is a cross-sectional View of a tube base embodying the present invention; Fig. 2 is an enlarged perspective View of a shield member forming part of said base as shown in Fig. 1; Fig. 3 is a plan view of the shield member shown in Fig. 2; Fig. 4 is an enlarged perspective view similar to Fig. 2, show ing a modified construction of the shield; Fig. 5 is a cross-sectional View similar to Fig. 1, showing a connection from the shield to the ground connection only; and Fig. 6 is a plan view of the shield member shown in Fig. 5.

In general, the preferred and illustrated embodiment of the present invention contemplates a novel construction of the base portion of an electronic tube in which various metallic portions of the tube are required to be connected to a terminal member in the base, and the present invention aims to provide a novel structure by which such connections may be simply and emciently made and which enables the tube to be more economically produced. The base portion of the tube preferably includes an insulating disk provided with the usual connection pins or members including a ground connection terminal. The insulating disk is also provided with an outer cylindrical metallic shell forming a cup shaped receptacle in which the glass portion of the tube is secured. The insulating disk is further provided with a central locater plug within which an inner metallic shielding member is disposed, and in the fabrication of the tube, it is necessary to connect the shielding member to the ground connection terminal for the purpose of grounding the shielding member.

In accordance with the present invention, a grounding lug or strap is formed integrally with the inner shielding member and is designed so that when assembled with the tube base, the strap will extend over the top of the ground connection terminal to which it may be secured in any suitable or preferred manner, such as by clamping the strap under the head of the terminal pin or by soldering or Welding the parts together. Thus, in the assembly of the tube, the operation of,securing a wire to the shielding member and inserting it into the hole in the terminal is eliminated, resulting in a saving of time and labor and reducing the cost of production to a minimum.

In accordance with the present invention, the usual step in the assembling operation of securing one end of a separate wire to the shell and soldering the other end thereof to one of the pins has also been eliminated by providing an extension from the integral strap to contact with the outer shell which may then be soldered, spot welded or otherwise suitably secured thereto to form an efficient mechanical and electrical connection from the shield to the ground connection terminal and from the latter to the outer shell.

Referring now to the drawing, Fig. 1 represents a tube which may comprise a bulb in containing the several elements of a thermionic valve, not shown, and a base portion or insulating disk [2 composed of dielectric material. The insulating disk 12 is provided with the usual contact terminals or pins l4 spaced about a central locating plug or key [6. The base also includes a cylindrical shell portion l8 composed of metal which fits over a ridge 2%] and on top of a shoulder 22 provided on the disk. The shell I8 is preferably secured to the disk 82 by bending the lower edge of the shell inwardly at selected points 24 into grooved portions 28 provided therefor, although, of course, it may be secured thereto in any other convenient manner. The base thus formed provides a cup shaped receptacle in which the bulb Ill is secured.

In the preferred embodiment of the invention, in order to provide an electrostatic and electromagnetic shield between the individual stem connection leads and between the individual terminal pins Id of the tube, a centrally disposed shielding member 28 is provided. As herein shown, the shielding member is cylindrical in form and is inserted into and extends above the hollow portion within the locator plug l6, as illustrated. As shown in Figs. 1 and 5, in order to provide an electrical connection between the shielding member 28 and one of the contact terminals or pins M for the purpose of grounding the shield, the latter is provided with an integral strap or lug 39, the shield and strap being preferably fabricated from one piece of metal. The strap 30 is preferably formed by slitting the cylindrical portion of the tubular shield and then bending this portion up at right angles to the axis of the shield as illustrated in Fig. 2. The strap thus formed is provided with a hole 32 which coincides with the center of one of the terminal pins I4 when assembled in the insulating disk l2. The metal connection pins I4 are secured to the insulating disk I2 by inserting them through the holes provided therefor and then swaging, crimping or bending over the extended portions thereof to clamp them in place. An enlarged portion 34 of the pins serves as a shoulder to engage the underside of the disk. In order to secure the strap connection 3!) to one of the terminal pins, the end of the terminal pin selected to serve as the ground connection terminal, is extended through a hole in the insulating disk and through the hole 32 in the strap and the extended end is likewise swaged or bent over the top of the strap, as illustrated. It will be understood that the method of securing the strap to the connection pin as herein shown, is merely illustrative and that any convenient method of securing the parts may be employed.

As shown in Figs. and 6, the strap connection 3i] extends only to the ground connection pin. However, in practice, it is preferred to extend the strap beyond the connection pin as shown in Figs. 1 and 2, in order to provide a connection to the outer metallic shell l8. As therein shown, the extended portion 36 is bent up over the ridge 2!) and then flattened against the inner wall of the shell and the extension is then soldered, spot welded or otherwise secured to the shell, thus providing an integral ground connection between the shielding member 28 and the ground connection terminal and between the shell l8 and the ground connection terminal.

The shielding member 28, as illustrated in Fig. 2, is formed by rolling a fiat sheet of metal and bringing the longitudinal edges thereof into abutting relation. In this embodiment of the invention, an opening 38 is left in the cylindrical member when the strap portion 39 is bent up-. wardly as shown in Fig. 2. This opening 38 in the shield is not obj'ectional and does not detract from its shielding characteristics when facing the ground connection terminal. However, when it is desired to provide a completely shielded structure, the shielding member may take the form illustrated in Fig. 4, wherein the longitudinal edges of the metal are overlapped a distance equal to the width of the integral strap 30, as clearly shown in Fig. 4.

From the above description it will be observed that the present invention provides a simple and emcient grounding connection between the inner shielding member 28 and the ground connection terminal and from the outer shell 13 to the same terminal, and as a result of the novel construction of such grounding connections, the assembly of the tube base is facilitated and the number of assembly operations is reduced whereby a substantial saving may be made in the cost of production of the tubes.

For some purposes, the metallic shell l8 may have fitted in telescoping relation thereon or thereover, an outer metallic shield member indicated in dotted lines in Fig. 1 as Id.

The present tube base is particularly useful in the manufacture of electron discharge tubes, vacuum tubes, gaseous discharge tubes, thermionic valves, cathode ray tubes, and any other electronic tubes or devices, and in its broader aspects, the invention finds utility as a novel and highly useful electrical connector.

While the preferred embodiment of the invention has been herein illustrated and described, it will be understood that the invention may be embodied in other forms within the scope of the following claims.

Having thus described the invention, what is claimed is:

1. A tube base comprising a disc of insulating material having a plurality of connection pins extending from one face of said disc, and spaced from the center of said disc, a cylindrical metal shell secured to said disc and extending from the other face of said disc adjacent the periphery thereof, said disc having a central opening therein, a metallic shield in said opening extending axially from said disc between oppositely disposed connecting pins for substantially their entire length and from said other face of said disc for a substantial distance within said cylindrical metallic shield, said shield being electrically connected to said cylindrical shell and to one of said pins.

2. A tube base comprising a disc of insulating material having a plurality of connection pins extending from one face of said disc, and spaced from the center of said disc, a cylindrical metal shell secured to said disc and extending from the other face of said disc adjacent the periphery thereof, said disc having a central opening therein, a metallic shield in said opening extending axially from said disc between oppositely disposed connecting pins for substantially their entire length and from said other face of said disc for a substantial distance within said cylindrical metallic shield, said shield having an integral strap extending outwardly adjacent said other face of said disc and being electrically connected to said cylindrical shell, said ,strap being provided with an aperture intermediate its ends, one of said pins extending through said aperture and being electrically connected to said strap.

3. A tube base comprising a disc of insulating material provided with a hollow centrally dis posed guide member of insulating material extending axially from one face thereof, a plurality of connecting pins extending from said one face of said disc, and spaced from the center of said disc, said pins surrounding said guide member, a cylindrical metal shell secured to said disc and extending from the other face of said disc adjacent the periphery thereof, a shield member positioned within said hollow guide member extending between oppositely disposed connecting pins for substantially their entire length and extending axially from said other face of said disc for a substantial distance within said cylindrical shell, said shield member iceing electrically connected to one of said cylindrical shell and said pins.

4. A tube base comprising a disc of insulating material provided with a hollow centrally disposed guide member of insulating material extending axially from one face thereof, a plurality of connecting pins extending from said one face of said disc, and spaced from the center of said disc, said pins surrounding said guide member, a cylindrical metal shell secured to said disc and extending from the other face or" said disc adjacent the periphery thereof, a shield member positioned within said hollow guide member extending between oppositely disposed connecting pins for substantially their entire length and extending axially from said other face of said disc for a substantial distance within said cylindrical shell, said shield member having an integral strap extending outwardly adjacent said other face of said disc, and being electrically connected to said cylindrical shell, said strap being provided with an aperture intermediate its ends, one of said pins extending through said aperture and being electrically connected to said strap.

BRUCE A. COFFIN. 

